Then there was the ill-fated PSFL -- Professional Spring Football League -- it was set to play in a non-traditional season, but never made it to the first week.
I like obscure, random leagues, like the WLAF, now NFL Eurpoe and how leagues like that can make NFL also-rans into starts, at least for a day.
Stan Gelbaugh, MVP of the initial WLAF season for the London Monarchs (great name) was mired with mediocricy, if that, in the NFL.
Jim Harbaugh once played for the Chicago Bruisers of the Arena Football League. Art Schliester, best known for gambling his life away, was an AFL legend for the Detroit Drive. I actually liked it when ESPN would play those old games late at night, I'd catch the Chicago Bruisers vs. Pittsburgh Gladiators with Adrian Karsten (rip) or some lame-o one the call, trying to break into broadcasting by doing tape-delayed arena football on some all-sports cable network.
Here's the wiki on the PSFL
http://en.wikipedia.org/wiki/PSFL